Crystal subharmonic generator



Aug- 30, 1932- w. ALBERsHx-:IM 1,874,845

CRYSTAL SUBHARMONIC GENERATOR Filed April 17, 1929 m V`. f9 I 3mm qui wwf: M

synchronization. Also, t

cies" Within'y lthis ra-ngezisextremely important Patented Aug. 3o, 1932 Immos; OFNEW Yon-K, NQY., A CORPORATION or1 DELAWARE`V verzars'rAL 1 sUnHAaMoNIC GENERATOR Application.,v medi April 17,

This invention relates tothe piezo-electric art and deals more specifically with amethod andV apparatus for producing oscillations at constant frequencies, which' are' lower than the fundamentalfrequencies; of crystals of "present day commercial sizes. 4 It is `well known thatfthel fundamental frequency of' a' piezoelectric crystal is an inverseeunction ofthe physical dimensions of thaticrylstaf, and therefore, when it is deaired tomtilize-erystal" control at frequencies hel'ow'th'e order of"100`,000" cycles per second, the crystafv necessary to maintain control at these vrelatively lower frequencies has fsuch la Y,dimensions that: it cannotbe procured wit ut prohibitive costanddifi'culty. There-is a great demandat the present 'time for means of? exactl'yjcontrolling frequencies helowtheorder ofi 100,000 cycles per secondi Frequencies of this order of magnitude ind use in time standards, telephotographic and television apparatus as well as other devices re airing mechanical (lie use of frequeniny the field of carriercommunication with w suppressed fundamentall frequency;

Itis, therefore, an object'ofthi's invention to provide a method and apparatus for generatingrefatively low frequency' oscillations undea-l cont-rol of a: piezoeelectric" resonator e having'commercially practical dimensions. It is a: furtlrerobject ofthis invention to generateoscillations cfa constant frequency, which* frequency is a suhharinonic of the fundamental frequency ofthe piezo-electric resonator-used.l I Y Further, itis an' object' Ofthis invention to. provide for the` generation. of oscillations at different constantL frequencies, under cone trolof'a single piezo#electric device.

It is afii'rtller object of this invention to generate constantfrequency oscillations and to vary the valueA of the particular frequency produced, Without necessitating the use of different crystals." Finally,it is an objectof this invention generally to improve the piezo-electric Vart asap'p'lied to its use in connection with maintaining Vfrequency of an oscillation genertion f 10W: .lastmentioned generatoris vassociated a frequency multiplying device, 'which is `constructed and arranged tolboosttherelatively 1929. vSerial No. 355,803.

ator constant, and more particularly asappliedto crystal control at frequencies lower Y than the frequencies at Whichcrystal control 'has heretoforeheen 'commercially practical.

The objectsof this invention briefly'are realizadas follows: f relatively high frequency oscillation generator is provided With a crystal controll devicel in a manner Well understood in the,

vartjatthe present time'. separate oscilla- Generator tuned to a desired relatively frequency is provided, vvand with this lou7 frequencies to a value Whichldiffers 'from the value of the frequency, of 4the `relatively highfrequency generatorby -an amount: equal Annmzanmx; or; New YORK, N. Y., AssIeNon To RADIO conzeonAfrroN 0F@ to the frequencydesired tov be used.` The harmonic or multiplied vfrequency of the aforesaid relatively lowfrequency generator together with the relatively high frequency oscillations; produced. under crystal control are `then fed into a modulatingtube, in the y,

output circuit of which tube there exists, among other frequencies, a'fr-equency equal .to the difference of the ,rela-tively high frequency andthe harmonic frequency. The

outputcircuit of the modulatortube is tuned to -this .last mentionedv frequency.

i e output circuit ofthe modulator tube is-'coupled tothe input circuit ofthe low frequency generator 4 whereby oscillations 4under crystal control are reiieXed or fed. back Y L thereto. The phase and amplitude of these oscillations produced under frequency controlrare adjusted to pullthe relatively low frequency generator into step l and the' loW sev frequency generator thereafter` operates to if .produce oscillations of ai frequency exactly equal tothe reflexed frequencies Wh1ch,1t

Will be remembered', remain constant due to the action of the `crystal on the high frequencyoscillation generator. v, Y

l Afspeciicv example Will be helpful inf` understanding. the foregoing principles:

Let us assume We Wish to produ-ce oscillations. ofy 20,000 lcycles per secondl under crystal control; The relatively low frequency generator is tuned to that frequency. The

harmonic generator is tuned to 80,000 cycles per second. lThe high frequency generator operating under crystal control is tuned to 100,000 cycles per second. This last mentioned frequency is modulated by the oscillations of 80,000 cycles and the 20,000 cycle oscillations thus produced are selected and reiiexed into the said relatively low frequency generator, thus causing it to pull into step, land to continue to oscillate at I20,000 cycles with substantially no variation.

The* manner in which this invention isY carried out will be more `readily understood Y from the following description taken in connection with the accompanyingdrawing in which the single ligure is a schematic dia1 gram of one specific embodiment of the presy ent intention.

Referring in detail vto the drawing, a low frequency oscillation generator 10, tuned by means of the resonant circuit 11 to a frequency, for example, of 20,000 cycles per second, has coupled-to it at 12 a frequency multiplying vacuum tube 13. The Atube 13 is provided with. a suitable biasing battery y1li which causes 'the tube to operate on a knee of its characteristic curve to insure the production of harmonics of the frequencies fed from the tube 10. The outputcircuit 15 of the tube .'13 is tuned, for example, to a frequency four times that of the frequencies produced at 10 or 80,000 cycles per second. Coupled at 16 to the harmonic generator 13 is a suitable amplifying device 17 which is adjusted to bring the amplitude of theharmonies up to the desired value. A second or high frequency oscillation generator tube 19 is coupled to the amplifier 17 at 18. The oscillation generator 19 is provided with a crystal control resonator 20 ina manner well known in the art. The oscillation generator 19 is provided with suitable biasing battery 21 and a choke coil 22. Itis to beunderstood that the structural details of the crystal controlled oscillation generator 19, perse, forms no part of the present invention, but rather any crystal controlled oscillation generator now known in the art may be used. The

loscillation generator represented herein may also serve asa mixing tube, or alternatively f separate tubes may be utilized, one for'Y the purpose ofr generating the oscillations and the other as a mixing tube for the oscillations produced fromthe frequency multiplier j 17 and the'high frequency generator. In the specific example being described, as already indicated above, the tube 10 produces oscilla-k tions of the frequency of 20,000 cycles, the tube 13 oscillations of 80,000 cycles, and the vtube 19 is made to oscillate independently at 100,000 cycles, under control of the crystal. The 100,000 cycle frequency is modulated in the tube'19 by the 80,000 cycle frequency produced in 13 and amplified in 17, with the result that, in the output circuit 23 of. the

Y While tube 19, there flows a frequency of 20,000

cycles, which frequency remains constant due to the action of the crystal 20 on the tube 19. The output circuit 23 of the tube 19 is coupled to the input circuit 11 of the tube 10 yat 211,*

whereby the relatively low frequencies, which are kept constant through thevaction of -the crystal 20, are reflexed into the tube 10. The amplitude and phase ofthe reflexed oscillations are adjusted to exceedthe Ygr.ids'vving of the tube 10.` virtueofthis arrange- `rnent the low l frequency oscillations pro- 'Y duced under crystal control pull the voscillation generatorr10 into step and cause yit* to oscillate exactly at the frequency of the revflexed oscillations,4 namely, 20,000 cycles. per

second. v

embodiment of the invention -it is to` be understood that many changes; in the system and method disclosed will readily suggesty themselves to thoseiskilled in the art. .For

example, any suitable number of stages of amplification may` be'futilized at any point inthe system without departing ffronn the ielsa anyfoner" several ofv the tubes?l shown may be used to.

spirit of this invention.

perform a single or dual function, such as, for example, the tube 19which serves as .both an oscillationgeneratorand a. modulating there is disclosed herein aA specific p tube. It is tobe strictly understood V that the vpresent disclosure ismerely used for thepurposeof illustrating the principles of this inventlon, and that they scope thereof y,isnot vto be limited except as outlined in theappended AJ* claims A l Having thus described `my invention, y.-I claim:`

1.r The method y'of producing electricaloscillations of substantially constant frequency which comprises,producing relatively-high 2. They method of producing cillations of substantially constantfrequency which comprises, producing. relatively high frequency oscillations undencontrol jo'f an y electro-mechanical vibrator, independently producing yrelatively lowy frequency oscillations, multiplying the frequency of said last mentioned oscillations toa value which differs from said first mentioned oscillations i approximately by an amount equal to the desired frequency of oscillation, andfcombining said multiplied oscillations with said first mentioned oscillations to produce oscillations having the desired frequen`cy.v z l .Y

tio

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32.. oiptoduning; electr-'icallosof substantially constant #frequency "tions, multiplying t e frequencyofsaid last -iyinentioned osciil'a'ti'ons toa value which difapproximately'by al1-:amount equal tothe desired frequency of'oscillation, combining, said multiplied oscillations with said first,

mentioned oscillations to produce oscillations having the desired frequency, and reexing the oscillations thus produced through said relatively low frequency producing Vapp'aratus. Y

4. The method of producing .electrical oscillations `of substantially constant fre- Q :3190 quency which comprises, producing relatively high frequency oscillations under control of a piezo-electric resonator, independently producing relatively low frequency oscilla- ?5 tions, multiplying the frequency of said last mentioned oscillations by means of said oscillations of multiplied frequency, and reiiexing said modulated oscillations through said relatively low frequency oscillation producing apparatus.l c

5. The method of producing electrical oscillations of substantially constant frequency which comprises, producing relatively high frequency oscillations under control of a piezo-electric resonator, independently producing relatively low frequency oscillations, multiplying the frequency of said last mentioned oscillations to a value which differs from said first mentioned oscillations approximately by an amount equal to the desired frequency of oscillation, combining said multiplied oscillations with said first mentioned oscillations to produce oscillations having the desired frequency, and reflexing'the oscillations thus produced through-said. relatively low frequency producing apparatus.

6. The method of producing electrical os-A cillations of substantially constant frequency Which comprises, producing relatively high frequency oscillations under control of an electro-mechanical vibrator, independently producing relatively low frequency oscillations, multiplying the frequency of said last mentioned oscillationsto a value different in frequency from the high frequency oscillations generated, modulating said first Vmentioned oscillations by means of said oscillations of multiplied frequency, utilizing said modulated oscillations to control the Vproduction of saidrelatively low frequency oscillations.

7 The method of producing electrical os- Vmentioned.- oscillations to` a value which differs.. from said first mentOned `oscillationsv approximately by an amount lequal tothe `desired frequency of- .oscillatiomand combining j said. multiplied oscillations:with` said iii-st "fers from said first mentioned oscillationsl 4 ing` low .frequency oscillations.

IeleCtnoi-mechanical "vibrator, independently producing relativel low frequency oscillawhich comprises, producing l nelatively high j i freqliencyy oscillations. `ander ,control of: an f 5jelectro-mechanical vibrator, independently produoingrelatiael low frequency oscillations,` multiplyingt ie frequency-of saidv last pull the relatively low frequency producing apparatus into-,step therewith. i

8.1Apparatus for producing oscillations ying in cOmbinat-iom, means to produce relajtively high. 'frequency oscillations, electromechanical means vto control said means, means tolgerierate relatlvely loW lfrequency oscillations, means to produce a harmonic pff-195 saidlast mentioned oscillations, ,meansto 'y combine said-relatively high frequencyg'os-` cillations with said harmonic, and `meanfsto ,reflex-l sai-d combined frequencyV intosaid mentioned oscillations, modulating said first means for-generating. low` frequency oscil-o lations. v .Y Y ,l

9.. Apparatus for producingv oscillations of `,substantially constant frequency` compris- Vmeans `to--producea harmonic of 4said last mentioned oscillations, means .-to combine saidn relatively high frequency loscillations with@1 saidgharmonidand means to reflex vsaid comlbined fnequency into said means forgeneratv:10. Apparatus for -producing oscillations ofsubstantially vconstant frequency. compris-5 `ingin combination, a crystal controlledyscillatingV vacuum tube tunedto agrelatively high frequency, means to `generate oscillations of a desired relatively low frequency, means` Acoupled to isaidlast mentioned means r.to pro-7110 duce a harmonic of said last mentioned oscillations,.rneans to impresssaid harmonic upon said vacuum tube whereby to modulate .the .oscillations produced thereby, and means r-t'o impress saidmodulated oscillations upon; saidC1115 first mentioned means. y .I Y,

,11. Apparatus: for producing oscillations of substantially constant frequency compris- ,ingin-combination, a crystal controlled osg c'illating vacuum tube tuned-,to arelatively* .high frequency,,vacuumv tube vmeans .to generate oscillations of Ya Vdesired relatively low frequency, .means coupled to. said lastmentioned means to produce a. harmonic .of said 25 last mentioned oscillations, means to impress ,said harmonic upon said-vacuum tube Wherebyf to modulate .the oscillations yproduced thereby, and' means to 'impress 4said fmodu- .latedV oscillations lupon' saidl first 'mentioned means," the 2amplitude of said y modulatedalo swing of'said secondr mentioned vacuum tube.v

estimations being adhered-t exeeeathe gridl2'. Apparatus for producing oscillations of substantially constant frequency compr-istion generator tuned to a relatively high frequency, piezo-electric means to maintain said frequency substantially constant, a second vacuuml tube oscillation generator tuned to va relatively vlovv Yfrequency, vacuumA tube means'to produce a harmonic of-sa-,id lastmening in combination, a vacuum tube 'oscilla- @fuerosanna@whoser feqenyfi t be i signature.

. tioned oscillations coupled to said last men-` i tioned generator, a modulating tube'fed by said' first mentioned vacuumftube and said A harmonlcg'enerator constructed and arranged l f vto combine said relatively high'frequencyos-l cillatlons With said harmonics, and means to 'reflex said combined 'frequencies into said '-lations. A

means for generatinglovv frequency oscil- 13;l The method of producingelectrica'l osl i '"cillations of substantialconstant frequency a l Whichf comprises generating;'substantially' p-"constant frequency highv frequency oscillations, generating independently relatively lovv frequency oscillations, multiplying the v *frequency of thelow frequency loscillations to a value different from that lofthe highV 'frequency oscillations generated, combining Atheoscillations 'of the multiplied frequency with" the high frequency oscillations, and utilizing the resultant oscillations '-tocontrol oscillations generated.

Y the frequency of the relatively low frequency Y Y 14. YApparatus for producing rrelatively` low frequency 'oscillations' of substantially "constant frequency comprising a high frequency oscillator generatingjo'scillations"of substantially constant "frequency',a lovv' fre'- i" quency oscillator, generating oscillationsat the desired lowfrequency, means for' multii yplying` the frequency'of said Vlovv` frequency n oscillations to al value such'th'at Whenbeaten with oscillations of said highl frequency oscillator the resulting be at oscillationsv have a frequency corresponding'to the frequency of Voscillation of saidlow frequency oscillation Y generator, and, means for applying'oscillai 'plied thereto.

tions of beatfrequency to said lowfrequency frequencyf oscillations so obtained tof-the lntestimony Whereoffvlhaveaixed "myy p WALTER IBERSHEIM@ la) a i fno oscillation generator whereby said lovv fre'- l quency oscillation generator n' is pulled into step'flwith the beat frequency oscillations apy l5, Apparatus for generating oscillations I of constant Afrequency comprising an oscillation generator Whose frequency is tobe controlled, an oscillation generator generatling oscillations of substantially constant frequency, means for frequency multiplying roscillations from the Voscillator Whosefrequency is to Vbe controlled, meansl for beating the frequency vmultiplied oscillations with oscillations ,from said constant frequency generator whereby to; obtain oscillations'` of afrequency Corresponding to the frequency l iso 

